High temperature transport properties of Ca3−Na Co4O9 system

Xu, Gaojie; Funahashi, Ryoji; Shikano, Masahiro; Pu, Qirong; Liu, Biao

doi:10.1016/s0038-1098(02)00495-7

Cited by 73 publications

(59 citation statements)

References 17 publications

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“…The substitution can take place either at the Ca-site or at the Co-site. There have been a number of reports on partially substituted elements at Ca-site, for instance, Na [11][12][13][14], Y [8], Ag [15][16][17][18], Bi [12,19], Ba [18], Nd [14], Gd [20], Yb [21], and other rare earth elements [22][23][24]. The effect of partial substitution at the Ca-site is mainly to change the charge carrier concentration which results in a change in resistivity.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of transition metals-doped Ca3Co3.8M0.2O9+δ (M = Co, Cr, Fe, Ni, Cu and Zn)

Pinitsoontorn

Lerssongkram

Keawprak

et al. 2011

J Mater Sci: Mater Electron

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The thermoelectric properties of the Ca 3 Co 4 O 9?d and the transition metals-doped Ca 3 Co 3.8 M 0.2 O 9?d (where M = Cr, Fe, Ni, Cu and Zn) ceramics were reported. Ca 3 Co 4 O 9?d single phase was checked by using X-ray diffraction analysis performed for the Ca 3 Co 3.8-M 0.2 O 9?d samples. The scanning electron micrographs showed some degrees of grains alignment in the compacted direction. The resistivity of the samples measured from 100 up to 700°C varies in magnitude for different transition metals substitution. The variation of resistivity was explained by a change of carrier concentration induced by the doped ions. The thermopower increased with increasing temperature but showed no obvious change for any transition metals doping. The thermal conductivities changed for the doped samples but were relatively independent of temperature. The ZT was calculated to be the highest for the Fe substitution for the whole measurement temperature with the maximum value of 0.12 at 700°C.

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Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of transition metals-doped Ca3Co3.8M0.2O9+δ (M = Co, Cr, Fe, Ni, Cu and Zn)

Pinitsoontorn

Lerssongkram

Keawprak

et al. 2011

J Mater Sci: Mater Electron

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“…We studied the pristine system (i.e., the 5/3 rational approximation) as well as its behavior under tensile and compressive strain. The results are expected to be applicable for not too low temperature, T > ∼ 200 K. In order to explain the measured room-temperature resistivity [4], we have chosen the relaxation time to be given by 3 [32]. Note, however, that the reported resistivities vary considerably, ranging from ≃ 2 for single crystals [5] to ≃ 170 mΩ · cm for thin films fabricated on an LAO substrate using the PLD technique [22].…”

Section: Discussionmentioning

confidence: 99%

Thermoelectric properties of the misfit cobaltate Ca3Co4O9

Amin

Eckern

Schwingenschlögl

2017

Applied Physics Letters

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The layered misfit cobaltate Ca 3 Co 4 O 9 , also known as Ca 2 CoO 3 [CoO 2 ] 1.62 , is a promising p-type thermoelectric oxide. Employing density functional theory, we study its electronic structure and determine, on the basis of Boltzmann theory within the constant-relaxation-time approximation, the thermoelectric transport coefficients. The dependence on strain and temperature is determined.In particular, we find that the xx-component of the thermopower is strongly enhanced, while the yy-component is strongly reduced, when applying 2% tensile strain. A similar anisotropy is also found in the power factor. The temperature dependence of the conductivity in the a-b plane is found to be rather weak above 200 K, which clearly indicates that the experimentally observed transport properties are dominated by inhomogeneities arising during sample growth, i.e., are not intrinsic.

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“…Recently, a great deal of attention has been given to the layer structured oxide Ca 3 Co 4 O 9 [4e6]. This oxide consists of alternating single CdI 2 -type CoO 2 layers and triple rock-salt-type Ca 2 CoO 3 layers along the c-axis [7,8]. The transport properties of Ca 3 Co 4 O 9 are highly anisotropic due to its layered structure [9,10].…”

Section: Introductionmentioning

confidence: 99%